Development of wound healing models to study TGFβ3's effect on SMA
The goal of this study was to test the efficacy of transforming growth factor beta 3 (TGFβ3) in reducing α-smooth muscle actin (SMA) expression in two models—an ex vivo organ culture and an in vitro 3D cell construct—both of which closely mimic an in vivo environment. For the ex vivo organ culture system, a central 6.0 mm corneal keratectomy was performed on freshly excised rabbit globes The corneas were then excised, segregated into groups treated with 1.0 ng/ml TGFβ1 or β3 (T1 or T3, respectively), and cultured for 2 weeks. The corneas were assessed for levels of haze and analyzed for SMA mRNA levels. For the 3D in vitro model, rabbit corneal fibroblasts (RbCFs) were cultured for 4 weeks on poly-transwell membranes in Eagle's minimum essential media (EMEM) + 10% FBS + 0.5 mM vitamin C ± 0.1 ng/ml T1 or T3. At the end of 4 weeks, the constructs were processed for analysis by indirect-immunofluorescence (IF) and RT-qPCR. The RT-qPCR data showed that SMA mRNA expression in T3 samples for both models was significantly lower (p < 0.05) than T1 treatment (around 3-fold in ex vivo and 2-fold in constructs). T3 also reduced the amount of scarring in ex vivo corneas as compared with the T1 samples. IF data from RbCF constructs confirmed that T3-treated samples had up to 4-fold (p < 0.05) lower levels of SMA protein expression than samples treated with T1. These results show that T3 when compared to T1 decreases the expression of SMA in both ex vivo organ culture and in vitro 3D cell construct models. Understanding the mechanism of T3's action in these systems and how they differ from simple cell culture models, may potentially help in developing T3 as an anti-scarring therapy.